Texas Instruments TLVH431CDBZT

Overview

TLVH431CDBZT from Texas Instruments is a low-voltage adjustable precision shunt regulator in SOT-23-3 package, featuring 1.24 V reference voltage (±1.5% at 25°C), 100 μA to 70 mA cathode current range, and operation from –40°C to +125°C. It replaces Zener diodes in secondary-side regulation of isolated flyback SMPSs and serves as an integrated-reference comparator for power-rail monitoring.

For engineers reviewing the TLVH431CDBZT datasheet, TLVH431CDBZT pinout, TLVH431CDBZT application, or TLVH431CDBZT equivalent, key selection criteria include reference tolerance grade (C = ±1.5%), cathode-to-anode voltage range (1.24 V to 18 V), dynamic impedance (0.25 Ω typical), thermal stability over industrial temperature range, and compatibility with optocoupler-based feedback loops in 3.3 V systems.

Technical Context

The TLVH431CDBZT implements a three-terminal shunt-regulator architecture with an internal 1.24 V bandgap reference and high-gain error amplifier driving a Darlington output stage. Its open-loop mode enables comparator functionality with built-in reference, while closed-loop operation-using external resistive dividers between cathode and reference pins-achieves precise adjustable output regulation.

Unlike the TL431, it operates down to 1.24 V cathode-anode voltage and requires only 100 μA minimum cathode current for regulation. The device is internally compensated and stable without output capacitance, though phase margin versus capacitive load is characterized up to 100 nF for design guidance.

Key Specifications

Pinout & Package

SOT-23-3 package (2.92 mm × 1.30 mm body size) with gull-wing leads; compact footprint suitable for space-constrained power management layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar shunt-regulator applications.

Compared with TLVH431CDBZT, TLVH431IDBZT offers improved reference accuracy at room temperature but sacrifices high-temperature performance, while TLVH432CDBZT delivers identical regulation behavior with inverted pin order-requiring layout change but no circuit redesign.

Availability

TLVH431CDBZT is available at Aetrix Electronics and suitable for isolated SMPS feedback, power-rail monitoring, precision ADC references, and adjustable LDO trimming requiring stable component supply across automotive, industrial, and telecom applications.

Supply support for TLVH431CDBZT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies with over 50 years of innovation in precision analog ICs.

The TLVH431 family was designed to replace discrete Zener diodes in low-voltage, high-accuracy shunt regulation-targeting isolated power supplies, voltage supervision, and reference generation in space- and power-constrained systems.

FAQ

What is the reference voltage tolerance of TLVH431CDBZT at 25°C?

The TLVH431CDBZT has a reference voltage tolerance of ±1.5% at 25°C, corresponding to a 1.24 V nominal value ranging from 1.221 V to 1.259 V. This C-grade tolerance is specified per TI's SLVS555N datasheet Section 5.5, and applies across the full operating temperature range of –40°C to +125°C for the Q-qualified variant. The TLVH431CDBZT maintains this tolerance without requiring external calibration.

Can TLVH431CDBZT operate with cathode voltage below 2.5 V?

Yes, TLVH431CDBZT is specifically designed for low-voltage operation starting at 1.24 V cathode-to-anode voltage-unlike the TL431 which requires ≥2.5 V. It regulates stably down to 1.24 V and supports output programming up to 18 V using external resistors. This capability makes TLVH431CDBZT suitable for 1.8 V, 2.5 V, and 3.3 V system rails where traditional shunt references fail.

What is the minimum cathode current required for regulation in TLVH431CDBZT?

The TLVH431CDBZT requires a minimum cathode current of 100 μA to maintain regulation, as confirmed in Section 5.5 of the datasheet under IK(min). This value is valid across the full temperature range and is significantly lower than the 1 mA minimum for TL431, enabling ultra-low-power monitoring and energy-harvesting applications where supply current is tightly constrained.

Does TLVH431CDBZT require an output capacitor for stability?

No, TLVH431CDBZT is internally compensated and remains stable without an output capacitor between cathode and anode. This eliminates ESR-related instability risks common in capacitor-dependent regulators. However, if an output capacitor is used-for noise filtering or transient response-the datasheet provides phase-margin vs. capacitive-load curves (Figures 5-15 to 5-17) to guide selection up to 100 nF.

How does the pinout of TLVH431CDBZT differ from TLVH432CDBZT?

TLVH431CDBZT uses CATHODE–REF–ANODE pin order (Pin 1–2–3), whereas TLVH432CDBZT uses REF–CATHODE–ANODE (Pin 1–2–3). Both share the same SOT-23-3 package and electrical specifications, but the pinout difference mandates PCB layout changes. The TLVH431CDBZT pinout aligns with legacy TL431 layouts, easing drop-in replacement in existing designs.